A multicast technology refers to a network technology in which one host sends a single data packet to multiple specific hosts at a time. Multicast is one of basic communications modes in the Internet. As point-to-multipoint communication, multicast is also a highly effective network bandwidth saving method.
A multipoint video conferencing system is a common application scenario of the multicast technology. A multipoint control unit (MCU) of the video conferencing system may be considered as a special-purpose server. In a multiparty conference, all conference parties are connected to the MCU. An audio and video sending device sends its audio and video stream to the MCU, and the MCU copies and then distributes the audio and video stream to each receiving device. Therefore, the audio and video sending device needs to send only one audio and video stream. The MCU completes star or tree networking for conference parties. In a sense, the MCU may be viewed as a switch that is specific to a video conferencing service and has a special function. A disadvantage of implementing the multipoint video conferencing system using the MCU is that, in MCU networking, a large quantity of dedicated devices is required, networking costs are relatively high, and network expansion is inconvenient.